NEW DELHI, India — Bacteria living in the mouth may play a critical role in gut health and could help predict the risk of chronic liver disease, according to a new study published in the journal Nature Microbiology.
More than two million people worldwide die each year from advanced chronic liver disease, underscoring the need for earlier detection and new treatment strategies.
In the study, researchers analyzed bacterial populations in saliva and stool samples from 86 patients with varying stages of liver disease. The team, led by scientists from the Technical University of Munich in Germany, found that both the gut and oral microbiomes undergo significant changes as liver disease progresses. Notably, changes in the oral microbiome were detectable at much earlier stages of the disease.
In healthy individuals, bacterial communities typically differ significantly between body sites such as the mouth and the gut. However, in patients with liver disease, the researchers observed that the oral and gut microbiomes became increasingly similar as the condition worsened. In advanced cases, nearly identical bacterial strains were found in both the mouth and the gut.
“These strains are typically found in the mouth and are rarely present in the healthy gut. However, we observed increases in the absolute abundances of these oral bacteria in patients with advanced chronic liver disease,” said Melanie Schirmer, Professor of Translational Microbiome Data Integration at the Technical University of Munich.
“This strongly suggests that these bacteria translocate from the mouth and colonise the gut,” she added.
The researchers identified several oral bacterial species that had colonized the gut in patients with advanced disease. Higher levels of these bacteria in stool samples were also linked to damage to the intestinal barrier.
Further genetic analysis revealed that these bacteria carry genes encoding enzymes capable of breaking down collagen, a key structural component of the gut lining. Laboratory testing confirmed that the enzymes were active.
“Collagen breakdown can compromise the gut barrier, potentially allowing bacteria and bacterial products to reach other organs, such as the liver. We believe this may worsen the disease,” said Aurelie Cenier, a doctoral researcher and co-first author of the study.
The findings point to new potential therapeutic approaches, including targeting the oral microbiome or strengthening the gut barrier to slow disease progression.
“Our findings open potential new therapeutic strategies for people with advanced chronic liver disease. Protecting or restoring the gut barrier could help slow disease progression. Targeting the oral microbiome offers a way to positively influence the course of the disease and prevent clinical complications,” said Dr. Vishal Patel of King’s College London. (Source: IANS)
